Method of inhibiting waxy deposits in oil wells and compositions therefor



METHOD OF INHIBITING WAXY DEPOSITS IN 01L WELLS AND COMPOSITIONS THEREFOR Edison G. Lee, Bellaire, Tex., and Helen P. Brush, Painesville, Ohio, assignors to Diamond Aihali Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Application March 11, 1954, Serial No. 415,693

16 Claims. (Cl. 252-8.55)

This invention relates to the treatment of parafiin waxbearing petroleum materials. More particularly, the invention relates to a composition for treating oil and gas wells and the equipment associated therewith to preclude and/ or minimize deposition of paraffin-type wax material therein, and to a process for utilizing such composition.

One of the most troublesome problems in the production, storage, and transmission of crude oil and gas heretofore has been the deposition of paraflin wax materials within wells, pumps, pipe lines, and storage equipment. As used herein, the expression paraflin wax is intended to include the various tars, waxes, paraffin, asphalts, as well as the wax-like deposits containing sulfur compounds, silicas, calcium salts, magnesium salts, sodium salts, and some crude oil. Such materials, both soluble and insoluble, deposit out of the oil or gas and clog passageways in the production, storage, and transmission equipment.

The rapidity and severity of deposition of these materials vary from field to field and, in fact, from well to well in the same field. In some instances, wax trouble is unknown, While in others, the paralfin wax begins to deposit as soon as a well is put on production. Moreover, some wells will produce for years without any substantial deposition of parafiin wax and then suddenly will become clogged with the deposited wax material. Perhaps the most expensive difiiculties are those caused by wax deposits on snub-surface equipment. For example, in a flowing well, paraffin wax may build up sufficiently within the tubing to shut off entirely the flow of oil, even When the normal fiow pressure is as high as 3500 p. s. i.

In the past, one solution attempted has been to run circular or spiral knives on wire lines through the tubing to cut off the wax and allow it to be flushed out of the well with the produced oil. However, such a method leaves much to be desired, since not only is such equipment and treatment costly, but such a cleaning process is also rather time consuming.

Many so-called parafiin solvents, intended to dissolve the parafiin wax material, have heretofore been tried. Some of these solvents include carbon disulfide, kerosene, gasoline, and carbon tetrachloride. However, prior solvents have either failed to dissolve the troublesome materials or have been too costly to be commercially feasible.

It now has been discovered that the aforementioned difliculties with paraffin wax deposition can be avoided entirely, or minimized, by the practice of the present invention, which comprises the use of a mixture of a halogenated olefinic compound and a halogenated aromatic compound as a paraflin wax solvent or treating fluid.

More particularly, the present invention comprises the use of a mixture of a chlorinated olefinic compound and a chlorobenzene, the preferred composition consisting essentially of a mixture of a material selected from the class consisting of perchlorethylene and trichlorethylene and trichlorobenzene. In most instances, superior results are obtained if a small amount of a non-ionic wetting agent is added to the foregoing composition.

In certain applications, the aforementioned composi' tion, with or without the non-ionic wetting agent, may' also contain a minor amount of a substance selected from the class consisting of carbon disulfide, kerosene, carbon tetrachloride, benzene, gasoline, petroleum naphtha,

monoand dichlorobenzene, ethylene dichloride, monoand dichlorethylene, and mixtures thereof.

In practice, the use of a treating fiuid of the present invention depends, of course, on the particular paraflin wax problem encountered. For example, in a. typical oil well, which consists of a tubular casing extending several thousand feet into the ground, and an inner tubing which extends to the oil level, it is generally desirable to inject a fluid of the present invention into the annulus between the well tubing and the casing at an initial rate suflicient to clean the well slowly from the bottom of the paraflin deposit. The injection rate may then be adjusted as necessary for the individual well in order to continuously keep the equipment clean. Similar injections of a composition of the present invention into pipe lines and storage equipment produce excellent results in removing paralfin wax deposits. Another method of application comprises the introduction of the treating fluid of the present invention into oil well flow lines, where .it is allowed to remain for a period of time, typically overnight. Such a treatment successfully removes clogging paraffin wax.

deposits.

It will be understood, of course, that the present invention contemplates not only the use of chemically pu-re compounds, i. e., perchlorethylene, trichlor'ethylene, and trichlorobenzene, for example, but also commercially available compounds. A suitable trichlorobenzene has the following composition:

72.0% 1,2,4 isomer trichlorobenzene 27.0% 1,2,3 isomer trichlorobenzene 0.2% 1,2,4,5 tetrachlorobenzene 0.5% 1,2,3,5 tetrachlorobenbene 0.3% high boilers polychlorobenzenes A broader composition range of satisfactory trichlorobenzene products is the following:

68% dichlorobenzene -85% trichlorobenzene 4-6% tetrachlorobenzene 13% higher and lower boilers Small amounts of monochlorobenzene, pentaand hexachlorobenzene Similarly, the perchlorethylene or trichlorethylene employed need not be chemically pure and may contain a stabilizer such as nitropropane or other nitroor chloroderivatives of ethane and propane. A typical satisfactory crude perchlorethylene composition is the following:

75% perchlorethylene 10-15% light ends 440% heavy ends The particular wetting agent employed will depend on a number of factors, including the particular petroleum material being treated and the problem encountered. However, typical of oil soluble, non-ionic materials which are suitable, in addition to diglycol oleate, are diglycol laurate, diglycol stearate, alkyl aryl polyether alcohols, fatty acid condensation products of polyhydric alcohols, long chain fatty acid esters, and polyethylene glycol esters of oleic acid. Suitable commercially available non-ionic wetting agents include Diglycol Oleate S, Triton X-45, Emcol H-50A, Mulsor, Detergent I-160, Nonisol 210, and Napco 2251-B.

By way of example, the following compositions, wherein the quantities are expressed in parts by weight,

Patented Sept. 3, 1

are illustrative oftreatin'g' fluids embodying the present invention: V V m i 7 Example I Perchlorethlylene ('s p.'xgr'avity 1.62.): l

Trichlorobenzene Example 11 I Berchlorethylene .L 50 Trichlorobenzene s V Diglycol oleate 0.5

l I Example III Perchlorethylene 40 Trichlorobenz ene '40 Kerosene 20 x Er mp Rerchlorethylene 40 Trichlorobenzene. n 40 Ks os i a g -qua 20 Alkyl ar-yl polyether alcohol (non-ionic wetting agent) 0.5

g 1 Example V 'Perchlorethylene 40 Trichlorobenzene 50 Carbon tetrachloride I Example VI Pe r chlorethylene 60 Trichlorobenzene 40 w w Example VII 7 'I richlorethylene 5 0 Trichlorobenzene 50 1, ExampleVIII Trichlorethylene 50 Trichlorobenzene 50 Non-ionic Wetting agent 0.5

It will be understood, of course, that the foregoing examples are illustrative only and that the compositions may be varied, depending on the particular application intended. However, at present, the preferred composition consists essentially of 50% by weight of perchlorethylene and 50% by Weight of trichlorobenzene with a small but effective amount, not in excess of about 4%, typically 0.5 to 2%, by weight of the perchlorethylene and trichlorobenzene, of an oil soluble non-ionic wetting agent, such as diglycol oleate. As a general guide, it is desirable to employ a mixture in which the halogenated olefinic compound and the halogenated aromatic compound are in approximately equal proportions. When a third fluid is employed, it should generally constitute a relatively minor part of the final blend, i. e., up to about 40% by weight. Similarly, While the amount of wetting agent to be employed will depend upon" the particular fluid used, and the application intended, it generally should not exceed about 4% by weight of the fluid blend, amounts as small as 0.20% being satisfactory in many instances.

By Way of an example of the effectiveness of compositions of the present invention, a mixture of 50% by weight of-Iperchlorethylene, 50% by weight of trichlorobenzene, and 0.5% of diglycol oleate based on the weight of the solvent blend is injected into a two-inch hydraulic pipe line in a south Louisiana field. The pipe line is approximately two miles long and operates under a working pressure of about 6500 p. s. i. and serves to carry the production ofa gas/distillate well to a central separator and regulator system. Normal production carried by the pipe is approximately 2.5 million cubic feet of gas per day, together with an unknown amount of distillate. Under normal operating conditions, the line be.- comesplugged with paraflin Wax material once or twice in a" day and numerous -prior-*parafiin solvents, 'even when injected at high rates, are ineffective to reduce the plugging; "However, the fluid material of the present invention prevents clogging of the line for at least 3 days, the length of time depending on the proper control of the fluid injection.

The same mixture of the present invention is also effective in the treatment of so called tank bottoms,

- which consist of crude oil, paraffin, dirt, and oil well brine in stable combination. For example, in a southeast Texas field, tank botttorn's are successfully treated by adding about 5 gallons of a rnixture of 50% by Weight of trichlorobenzene, 50% by weight of perchlorethylene, and 0.5% by weight of diglycol oleate,based on the foregoing blend, to 75 100 barrels of tank bottoms. 'The resultant mass is, agitated. with gas and allowed to settle overnight, whereupon water, which settles to the bottom, is drained off. The thus treated tank bottoms are mixed with crude oil and form asatisfactory salable crude oil material. 7

From the foregoing description it will now be understood that the. present invention provides a practicable treatment. for removing paratfin wax. material deposits from oil well tubing, pipe lines, and related equipment and preventing redeposit therein, as .well as a treatment for tank bottoms, thereby. permitting the salvaging of salable oil from a heretofore salable material.

7 While there have been described various embodiments of the invention, the methods and products'described are not intended to be understood as limiting the scope of the invention, as it is realized that changes therewithin are possible, and it is further intended that each element recited inany of the following claims is to be understood asreferring to all equivalent elements for accomplishing substantially the same results in substan-.

compound, and a minor amount of a non-ionic wetting agent, said mixture having improved. oil well wax solvent properties.

' 3. A composition of matter consisting essentially of substantial quantities of a material selected from the group consisting of trichlorethylene and perchlorethylene and a liquid halogenated aromatic compound, said a composition having improvedoil well wax solvent properties.

v 4. A composition of matter consisting essentially of a mixture of substantial quantities of chlorobenzene and a liquid halogenated ethylenic compound, said composition having improved oil well wax solvent properties.

5. A composition of matter consisting essentially of a ,mixture of substantial quantities of a liquid halogenated ethylenic compound and trichlorobenzene, said composition having improved oil well wax solvent properties. i

6. A composition of matter consisting essentially of a mixture of substantial quantities of trichlor'obenzene and a material selected from the group consisting of trichl0rethylene and perchlorethylene, said composition having improved oil well wax solvent properties.

7. A composition of matter consisting essentially of a mixture of substantial quantities of t'richlorobenzene and penchlo rethylene, and-a lesser amount of a substance selected from the group consisting of carbon tetrachloride, kerosene, benzene, gasoline, carbon disulfide, petroleum naphtha, mono-, and dichlorobenzene, ethylene dichloride, monoand 'dichl'orethylene, and mixtures thereof, said composition having improved oil well wax solvent properties.

8. A composition of matter consisting essentially of a mixture of substantial quantities of trichlorobenzene and a material selected from the group consisting of trichlorethylene and perchlorethylene and a minor amount of a non-ionic wetting agent, said composition having improved oil well Wax solvent properties.

9. A composition as in claim 8 in which the non-ionic wetting agent is diglycol oleate.

10. A composition of matter consisting essentially of a mixture of substantial quantities of trichlorobenzene and a material selected from the group consisting of trichlorethylene and perchlorethylene, and a lesser amount of carbon tetrachloride, said composition having improved oil well wax solvent properties.

11. A composition of matter consisting essentially of a mixture of substantial quantities of trichlorobenzene and a material selected from the group consisting of trichlorethylene and perchlorethylene, and a lesser amount of kerosene, said composition having improved oil well wax solvent properties.

12. A composition of matter consisting essentially of a mixture of substantial quantities of trichlorobenzene and a material selected from the group consisting of trichlorethylene and perchlorethylene, a lesser amount of carbon tetrachloride, and a minor amount of a non-ionic wetting agent, said composition having improved oil well wax solvent properties.

13. A composition of matter consisting essentially of a mixture of substantial quantities of trichlorobenzene and a material selected from the group consisting of trichlorethylene and perchlorethylene, and a lesser amount of kerosene, and a minor amount of a non-ionic Wetting agent, said composition having improved oil well wax solvent properties.

14. In the treatment of oil and gas Well efiluent, the

improvement which consists of injecting into the efliuent circulatory system a material consisting essentially of a mixture of substantial quantities of a liquid halogenated ethylenic compound, a liquid halogenated aromatic compound, and a minor amount of a non-ionic wetting agent, said material having improved oil well Wax solvent properties.

15. The method of treating oil and gas well production, storage, and transmission equipment, which comprises the steps of treating said equipment with a material consisting essentially of a mixture of substantial quantities of a substance selected from the group consisting of trichlorethylone and perchlorethylene, and trichlorobenzene, agitating such material within said equipment, and allowing material suspended by such treatment to settle.

16. A method of removing paraffin wax deposits from an oil well structure comprising a tubular casing and an inner tube, said method comprising the steps of injecting into the annulus around said tube a material consisting essentially of a mixture of substantial quantities of a substance selected from the group consisting of trichlorethylone and perchlorethylene and trichlorobenzene, and a minor amount of a non-ionic wetting agent, said mixture having improved oil well wax solvent properties.

References Cited in the file of this patent UNITED STATES PATENTS 1,861,177 De Groote May 31, 1932 1,938,714 Mills et al Dec. 12, 1933 2,017,327 Sullivan Oct. 12, 1935 2,225,434 Harrigan Dec. 17, 1940 OTHER REFERENCES Mellan: Industrial Solvents, second edition, pages 365 and 366 (1950), published by Reinhold. Pub. Corp., of New York, N. Y. 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY MIXTURE OF SUBSTANTIAL QUANTITIES OF A HALOGENATED ETHYLENIC COMPOUND AND A LIQUID HALOGENATED AROMATIC COMPOUND, SAID MIXTURE HAVING IMPROVED OIL WELL WAX SOLVENT PROPERTIES. 